The In general as a method to discharge melt inside melting furnace, tilting melting furnace itself or passing over overflow-dam in the upper part in melting furnace is used.
In addition, there is a method to discharge melt inside melting furnace by removing plug mounted on melt outlet or securing outlet with oxygen welding heat or oxidation heat of oxygen lance.
Recently, tapping method using induction heating method is under development and precisely there is respectively characteristic equipment unit.
Particularly, for PEM or IET in the U.S. tapping is performed using the side of flat bottom level of melting furnace in induction heating method.
Those tapping devices and methods for melt as described above are mostly for tapping melt of viscosity which is low or easy to be maintained like glass, and they are not proper for highly viscous material.
Particularly, in case of melt or glass-ceramic melt, its viscosity characteristic is distinctly different from glass melt, thus when it is exposed to outside through tapping hole, viscosity of melt grows rapidly and tapping can be stopped or become unsmooth.
And even if tapping can be performed, there is a problem that a container for melt is not be fully filled, melt is coming up like growing stalagmite.